Classifying relationships that define interactions between native and invasive species in Australian ecosystems

Australia was isolated for approximately 40 million years from the presence of eutherian predation until the introduction of the dingo (Canis familiaris; 4000 years ago), foxes (Vulpes vulpes; 1871) and feral cats (Felis catus; post-1788). The arrival of these invasive species coincides with the decline and extinction of many native mammals, specifically within the critical weight range (35-5500 g). These extinctions are likely a result of competition and predation, where locomotor performance and the associated behaviours contribute largely to overall fitness. We used the population responses of native fauna in the presence of introduced predators to establish a research framework. Introduction/extinction timelines, predator diets, and prey occurrence were used to identify invasive/native relationships where predation may define the population outcome. We then examined the locomotor performance of these species using current data (maximum speeds). Consumption of prey items does not seem to be associated with the probability of the predator encountering the prey. Dingoes had the most variable mammalian prey of all invasive predators, likely due to higher maximal speeds. Feral cats favour Dasyuridae and smaller species, preying upon these prey groups more than dingoes and foxes. The role of locomotor performance in invasive ecology is not well understood; we identified relationships for further exploration.